First, though, I laid out the tails full size and played around with sizes to get something that looked right. I ended up with this:

And the result was:

They are a bit loose as a result of me trying to see pencil lines on the dark end grain of the jatoba. Fixable, but I’ll be using the masking tape trick to do the other end.

Before fitting the end cap, I decided to clean up the shoulders of the end tenon. I had noticed some flex in the circular saw I used to cut the shoulders which meant that they weren’t consistently 90° to the surface. Get out the router and short pattern bit (well, it was already out from cutting the condor tail sockets) and square the shoulder and very lightly clean up the cheek of the tenon.

Also cut off the ends of the tenon with a hand saw. Didn’t need to be terribly precise:

As I used the long pattern bit to clean that up:

Led to:

I thought I had the bit extended to just past halfway, but after I turned it over and did the same thing from the other surface it turns out I was about 1/32” short. The rest was easy to clean off with a chisel.

Next step was to mortise the cavity into the end cap. Router motising jig to get most of it and then chisels to square off the ends:

I made the cavity slightly (< 1/32”) under width, so when I flipped over the slab to clean the tenon shoulder and cheek with the router, I was able to trim the cheek to get a perfect fit.

How does it fit?

A couple problems became apparent.

First, the tenon is not a consistent length. I set my mortise depth from one end of the tenon, looks like the other end is 1/16” long. I tried to use a block plane to trim the tenon down, but taking off 1/16” of end grain with a hand plane seems like a waste of time when I can use a router.

The other issue is that the shoulders do not line up. Either the collar jig I used was wonky (there’s a technical term for you) or the circ saw flexed a lot more than I thought. Or both. Probably both. Anyways, I’ll have to fix that, too, before I move on.

Terry, an end vise works wells, as a lot of these bench builds attest to. Put a dog hole in the moving jaw, you’ve got something that works like a wagon.

Why would those aprons interfere with adding a wagon vise? While I’m building my end cap breadboard-style, there’s no real need for that. An end cap can be bolted on (and mine will be), maybe using a spline to ensure vertical alignment. You could make yours the same size as the aprons, would give your bench an impressively beefy look.